Method for the production of lightmetal flasks with thickened neck parts



Sept. 20, 1938. H, R NA Z' 2,130,699

METHOD FOR THE PRODUCTION OF LIGHT METAL FLASKS WITH THICKENEDNECK'PARTS Filed-Nov. 12, 1937 1 71.3. fig. 4.

Patented Sept. 20, 1938- mm 1 STATE mrrnon FOR 'rnn raonocnon ornon-rmmn. msxs wrrn 'rnrcxnnnn NECK PARTS Heinrich Relnarts, Aachen,Germany, assignmmac-halt to Hans Amlaldern, Vienna, Ans- A pplicatlonNovember 12, 1937, Serial No. 174,148 In Germany July 2, 193B 2 Claims.:(ci. 29-1482) This invention relates to a method tor the production offlasks of light-metal for liquids and gases under high tension. .Theneck-portion of such flasks is weakened'thereby that a screwthread hasto be cut in; To avoid this weakening it is advisable to make thickerthan the other wall only the wall of the neck of the flask, in

order to keep as light as possible the weight of such flasks and so thatafter the screw thread has been cut into the neck the thickness of thewall of the neck at least corresponds to the thickness of the remainingwall portions.

In order to make the neck of steel bottles Ithicker, it has already beenproposed to press .15 onto the open end or the preliminarily drawncylindrical hollow body, in embracing the same by an insert-die, a presshead in axial direction, by the shape of whichthe en'd of the hollowbody is transformed into the shape of a bottle neck.

20 During the reducing oi the upper diameter of the hollow body anupsetting of the material in itself takes place and thereby an increaseof the wall thickness.

Up to the present the hollow body of a steel 25 bottle was continuouslycylindrical prior to the re-shaping or the neck, or its upper partwasthicker. Experiments have shown that, already with continuouscylindrical hollow bodies of light metal the radial resistance at theupper end of the bottle becomes so great that the hollow body especiallywithin the insert-die yields in inward direction in undulated shape,whereas an appreciable'thickening in the bottle neck does not occur atall. If the upper end of a bottle of lightmetal would be thickened priorto the re-shapw ing, the radial pressing resistance would beconsiderably increased, so that also the wave-tormation within theinsert-die occurs in increased measure. Owing to the narrowing. of thecrosssection .and accumulation of the material in the neck part a foldformation occurs further. By experiments it has been ascertained thatthese inconveniences can be avoided in light metal flasks in aquite-peculiar manner, if aca cording to the inventlon the upper portionor the flask is made conically thinner prior to the reshapin and thedrawingin of the bottle neck is carried out in several stages in such amanner that first the narrowing at the point of the thinning iscompleted which is farthest distant from the end of the hollow body,then in the middie and finally in the upper portion. The radialresistance or the wall surface against the narrowingis thereby graduallyreduced from the 55 point which has to be least narrowed up to the pointwhich has to be narrowed most, and the axial pressure upon the wall nottobe re-shaped is reduced also.

, The new method is illustrated by way of example in the accompanyingdrawing, in which I Fig. 1 shows the hollow body with the upper endconically thinner at the outer side.

Fig. 2 shows the hollow body after the first 5 narrowing,

' Fig. 3 after the second narrowing and Fig. 4 after the thirdnarrowing.

It must evidently be left to those skilled in the art to select three ormore narrowing. stages 10 according to the size of the flasks. Forcarrying out the new method as many diflerently shaped press-heads arerequired as narrowing stages exist. The first press head a engages onlyon the point of the conically thinned wall which has to be narrowedleast, whereby at this point a thickening of the wall occursapproximately on the distance 12 of Fig. 2. The second press head ceffects a thickening of the wall approximately on the distance d of Fig.3. The third press head 2 gives to the bottle neck the final shape, thethickening taking place particularly on the distance of Fig. .4. .Priorto every narrowing the bottle neck is heated to about 400. The newmethod can evidently be employed with all metals which relative to thenarrowing behave in a similar man her as aluminium-alloy.

I claim:

1. A'method for the production of light metal flasks with a thickenedneck portion for liquids and gases under high tension from apreliminarily drawn cylindrical hollow body, consisting in firstreducing the cross sectional area of the upper portion of the hollowbody and conically forming the same prior to the reshaping, and axiallyand radially compressing the conical end of the hollow body and therebyreducing the same to neck formation in sequential steps in transversezones toward the end of the neck and thereby moving the material of theconical end 40 to produce a neck wall thickness greater than thethickness of the wall of the flask.

2. A method for producing a cylindrical'metal container with arelatively thick walled neck' and a thin side wall of substantiallyminimum thickness to withstand predetermined high pres? sure of liquidsor gases consisting in first reducing the'thickness of the neck end ofthe cylinder into end tapering conical formation and then axially andradially compressing the conical end into a smaller diameter by pressingat a transverse zone inwardly of the conical end to increase the wallthickness 0! the neck portion and successively pressing the conical endat transverse zones toward the outer end of the neck.

